U.S. packaging company Ball Corp. is nearing a deal to buy U.K. rival Rexam PLC, according to people familiar with the matter, a move that would create the world’s largest beverage-can maker.

The companies said earlier this month they were negotiating a cash-and-share offer that would value Rexam at around £4 billion ($6.2 billion). But some analysts cited regulatory concerns as one impediment to the deal, as both companies have a...